It is also possible that some browser plugin reported that you accessed the domain. But in that case it would be more likely that you have a google or bing bot on your page and not some unknown bot/scanner/whatever.

You could simply exclude every IP but your own in the .htaccess if you need to be sure, you are the only one that can access the subdomain. (assuming your sever setup supports it)

e. g. if you have many rooms and the player moves in the building as does the enemy (AI). You could calculate the routes between the room at buildtime. Than you just lookup position (enemy room) and destination (player room) and have the best way. You can even have seperate calculations for different conditions like locked doors, spawned health packs etc.

As soon as player and enemy are in the same room you can use nearly any pathfinding algorithm for the 'last mile'.

Will it be really bad if I ask the user to enter his MAC address on my future website (right after he inputs his username, company name, etc.) instead of doing it automatically?

This might be a problem with business customers. The one buying the license might not know this information.E.g. I simply tell IT Service to buy X of that and Y of this, but usually i do not include the MAC Adresses. And to be honest, this extra work to collect all the information (computers might not be delivered for new employees. Existing ones are changed every few years), i would do this for an absolute must have software. Otherwise i would simply choose to buy a different product (if available).If you are not sure about the price of your software now, this might be something to think about before you invest time in a license server.You could simply offer a company or site license and be done with this problem. This is only a problem with really expensive software.